I believe you are correct, and there is a thread about it somewhere on this forum. His, if memory serves, was one of the nice Specials with braze-ons for bar end shifter cable stops and maybe even rear brake cable stops. Dates on these are somewhat unclear, but a while back I assembled this spreadsheet - https://docs.google.com/spreadsheets...h6HkE/htmlview - of Allegros, which seem to have an orderly, sequential serial number scheme postwar, if not earlier.